Question

我正在创建一个应用程序，我必须在启动画面中实现 alpha效果，当我加载图像时，它会给出null pointer exception。启动动画时的基本问题。如果我删除启动动画然后我的动画根本没有开始。我真的卡住。任何帮助将不胜感激。我的代码如下：

public class SplashScreen extends Activity {


private Thread mSplashThread;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);


    System.out.println("hello");
    setContentView(R.layout.splash);

    final SplashScreen sPlashScreen = this; 

    Animation a1 = AnimationUtils.loadAnimation(this, R.anim.alpha);
        LinearLayout Ll=(LinearLayout)findViewById(R.id.mainLayoutheader);
        System.out.println("hello1");
        Ll.startAnimation(a1);
         System.out.println("hello2");


    // The thread to wait for splash screen events
    mSplashThread =  new Thread(){
        @Override
        public void run(){
            try {
                synchronized(this){
                    // Wait given period of time or exit on touch

                   // a.reset();


                    wait(6000);
                }
            }
            catch(InterruptedException ex){                    
            }

            finish();

            // Run next activity
            Intent intent = new Intent();
            intent.setClass(sPlashScreen, Main.class);
            startActivity(intent);
            stop();                    
        }
    };

    mSplashThread.start();        
}

}

例外是L1.startAnimation(a1);

Answer 1

我猜你忘了拨打setContentView。你必须在调用findViewById之前这样做[编辑：这里没有解决问题]

Answer 2

Ll为null或a1为null，startAnimation抛出异常。完整的堆栈跟踪显示，哪一个扔了它。

此外：

您可能不小心输入了R.id.mainLayoutheader而不是R.id.mainLayoutHeader。
检查名称R.anim.alpha是否正确。

Answer 3

您可以尝试计时器线程...使用此链接 http://thedevelopersinfo.wordpress.com/2009/10/18/scheduling-a-timer-task-to-run-repeatedly/

Answer 4

问题是我显示图像的视图是空的 super.onCreate（savedInstanceState）;

    // Splash screen view
    System.out.println("hello");
    setContentView(R.layout.splash);
    ImageView iv=(ImageView)findViewById(R.id.splashscreen12);
    Animation scaleAnim = AnimationUtils.loadAnimation(this,R.anim.alpha);
    iv.startAnimation(scaleAnim);
    scaleAnim.setAnimationListener(new Animation.AnimationListener() {
    @Override
    public void onAnimationEnd(Animation animation) {
        // Start new activity after some delay
        TimerTask newActivity = new TimerTask() {
            @Override
            public void run() {
                startActivity(new Intent(SplashScreeen.this,CallingActivity.class));
                SplashScreeen.this.finish();

            }
        };
        Timer t = new Timer(false);
        t.schedule(newActivity, 2500);
    }

    @Override
    public void onAnimationRepeat(Animation animation) {
        // DO NOTHING

    }

    @Override
    public void onAnimationStart(Animation animation) {
        // DO NOTHING
    }
});

在启动画面的android：null指针

4 个答案: